1. Field of the Invention
The invention is related to telecommunication technologies, and in particular, to converged emergency service call handling technologies.
2. Description of the Prior Art
Service providers, such as telecommunication carriers, are required to provide emergency call services to end users. For example, service providers are typically required to offer 911 calling capabilities. Specialized location determining systems are used to determine the physical location of callers when 911 calls are placed.
Currently, determining the location of a caller on a circuit switched network, such as the public switched telephone network (PSTN), is a relatively straight forward task because every end point in the PSTN is fixed. The physical address of an end point, such as a home address, can be stored in association with a calling number, such as a home phone number. When a 911 call is placed from the PSTN, a location determining system performs a look up to a database system to determine the physical address of the call based on the calling number. The location determining system also determines the appropriate public safety answering point (PSAP) for the call and provides the physical address to the PSAP. In the meantime, the call is transferred from the PSTN to the PSAP.
Traditional wireless networks, such as CDMA, TDMA, GSM, iDEN, and PCS networks, present additional challenges to the task of locating callers. Namely, wireless end points are not fixed. Thus, wireless users can roam to any location at will. As a result, the location of a wireless caller cannot be determined based on his calling number. In response to this problem, complex location determining systems have been developed to assist with determining the location of wireless callers. For example, radio frequency triangulation techniques are used to locate callers.
Packet communication networks, such as the public Internet, present challenge beyond even those of traditional wireless networks. Voice services are often times provided over packet communication networks. An example of a packet based voice service is Voice Over Internet Protocol (VOID). Like wireless networks, VOIP end points are not fixed. Therefore, the location of a VOW caller cannot be determined based on his calling number or other similar type of identification. In response, complex location determining systems have also been developed in the prior art for determining the location of VOIP callers.
Oftentimes, a service provider provides both traditional wireless services as well as VOIP service. As a result, the single service provider frequently bears the entire cost of operating multiple location determining systems for both a wireless network and a VOIP network.
FIG. 1 illustrates communication network 100 in the prior art whereby a single service provider operates multiple location determining systems for both a traditional wireless network and a VOIP network. Communication network 100 includes public safety answering point (PSAP) 110 coupled to wireless location system 145 and VOIP location system 135. Wireless location system 145 is coupled to mobile switching center (MSC) 140. VOW location system 135 is coupled to VOW gateway system 130. MSC 140 is coupled to selective router 120 by trunk 101. VOIP gateway system 130 is also coupled to selective router 120 by trunk 102. Wireless phone 141 is in communication with MSC 140. VOIP phone 131 is in communication with VOIP gateway system 130.
FIG. 2 illustrates the operation of communication network 100 in an example of the prior art. A VOIP emergency call flow diagram is first described, followed by a description of a wireless emergency call flow diagram.
To begin, a VOIP user using VOIP phone 131 places an emergency call, such as by dialing 911. VOIP phone 131 responsively transmits the emergency call to VOIP gateway system 130. For instance, VOIP phone 131 might transmit the dialed digits along with a user identification that identifies the user to VOIP gateway system 130.
Upon receiving the emergency call and user identification, VOIP gateway system 130 initiates call setup for the emergency call by transmitting call setup signaling and the user identification to VOIP location system 135. VOIP location system 135 continues the call setup process by determining the location of the user based on the user identification. For example, VOIP location system 135 typically includes a location database that stores the physical address of users in association with their user identifications. In this case, VOIP location system 135 would perform a look-up to the location database based on the user identification.
After determining the location of the user, VOIP location system 135 generates a key that is used to identify the call. VOIP location system 135 continues the call setup process by transmitting the location of the user and the call key to PSAP 110. At the same time, VOIP location system 135 transmits the identity of the PSAP and the call key to VOIP gateway system 130. The PSAP is often times identified by a phone number. PSAP 110 receives the location information and the call key and waits for an incoming call associated with the call key.
VOIP gateway system 130 initiates call setup with selective router 120 by transmitting the PSAP identification and the call key to selective router 120. Selective router 120 responsively processes the PSAP identification to select the appropriate PSAP from a group of PSAPs. Selective router 120 then transmits call setup signaling to the selected PSAP, PSAP 110, indicating the call key. PSAP 110 receives the call setup signaling, recognizes the call key, and looks up the location of the caller based on the key provided by selective router 120. A bearer connection is established from VOIP phone 131 through VOIP gateway system 130, selective router 120, to PSAP 110. An operator at PSAP 110 is then able to direct emergency responders, such as the police, to the location of the caller.
In a wireless example, a wireless user using wireless phone 141 places an emergency call, such as by dialing 911. Wireless phone 141 responsively transmits the emergency call to MSC 140. Typically, wireless phone 141 transmits a user identification, such as a calling number, that MSC 140 can associate with the user.
Upon receiving the emergency call and user identification, MSC 140 initiates call setup for the emergency call by transmitting call setup signaling and the user identification to wireless location system 145. Wireless location system 145 continues the call setup process by determining the location of the user. Often times, the location of the user is determined using the global position system (GPS). Other times, the location of the user is determined using radio frequency triangulation techniques.
After determining the location of the user, wireless location system 145 generates a key that is used to identify the call going forward. Wireless location system 145 continues the call setup process by transmitting the location of the user and the call key to PSAP 110. At the same time, wireless location system 145 transmits the identity of the PSAP and the call key to MSC 140. The PSAP is often times identified by a phone number. PSAP 110 receives the location information and the call key and waits for an incoming call associaied with the call key.
MSC 140 initiates call setup with selective router 120 by transmitting the PSAP identification and the call key to selective router 120. Selective router 120 responsively processes the PSAP identification to select the appropriate PSAP from a group of PSAPs. Selective router 120 then transmits call setup signaling to the selected PSAP, PSAP 110, indicating the call key. PSAP 110 receives the call setup signaling, recognizes the call key, and looks up the location of the caller based on the key provided by selective router 120. A bearer connection is established from wireless phone 141, through MSC 140 and selective router 120, to PSAP 110. An operator at PSAP 110 is then able to direct emergency responders, such as the police, to the location of the caller.
As illustrated, communication network 100 in the prior art requires separate call handling processes for wireless emergency calls and VOIP emergency calls. Such a configuration is costly and inefficient. For example, two distinct trunks, trunks 101 and 102, are utilized to couple MSC 140 and VOIP gateway system 130 to selective router 120. Additionally, duplicate call handling processes are required in MSC 140 and VOIP gateway system 130 for routing emergency calls to selective router 120. Owning and operating multiple location determining systems for both wireless service and packet phone service problematically increases expenses and reduces operating efficiencies.